MOSCOW (Reuters) -- Russian prosecutors have charged nine members of a "criminal group" with the murders of three senior officials in the restive North Ossetia region, including the mayor of Vladikavkaz, officials have said.

Prosecutors said the gang shot dead the mayor of Vladikavkaz, Vitaly Karayev, on November 26, 2008, and killed his predecessor, Kazbek Pagiyev, a month later.

They said the gang also killed a senior police official and his son in the region in October 2008.

They were the highest-profile murders of officials in years, in a region rocked by a violent insurgency.

"Currently, three are in prison. An international search has been declared for the other six members of the criminal group," the Prosecutor-General's Investigative Committee said in the statement.

All nine have been charged, the statement said, adding that the six members it was searching for were Russian citizens.

It gave no motive for the murders.

Vladikavkaz is the capital of North Ossetia, a mainly Christian republic, which has been caught up in a wave of violence that began with a separatist rebellion in nearby Chechnya in the 1990s, and has since spread to neighboring regions.